lib/latch.h

   1 /*
   2  * Copyright (c) 2013 Nicira, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #ifndef LATCH_H
  18 #define LATCH_H 1
  19
  20 /* A thread-safe, signal-safe, pollable doorbell.
  21  *
  22  * This is a thin wrapper around a pipe that allows threads to notify each
  23  * other that an event has occurred in a signal-safe way  */
  24
  25 #include <stdbool.h>
  26 #include "util.h"
  27
  28 struct latch {
  29 #ifndef _WIN32
  30     int fds[2];
  31 #else
  32     HANDLE wevent;
  33     bool is_set;
  34 #endif
  35 };
  36
  37 void latch_init(struct latch *);
  38 void latch_destroy(struct latch *);
  39
  40 bool latch_poll(struct latch *);
  41 void latch_set(struct latch *);
  42
  43 bool latch_is_set(const struct latch *);
  44 void latch_wait_at(const struct latch *, const char *where);
  45 #define latch_wait(latch) latch_wait_at(latch, OVS_SOURCE_LOCATOR)
  46
  47 #endif /* latch.h */